AP Biology - Cell Communication + Cell Cycle

Quorum Sensing

How an organism makes itself known to other cells around them

Taxis

Movement of an organism in response to a stimulus, could either be positive or negative

Taxes

Innate behavioral responses or instincts

Chemotaxis

Movement in response to chemicals

Ligands

Bind to receptors and trigger a response by changing the shape of the receptor protein. Used in signaling

Receptors

Proteins whose shapes get changed when a ligand binds to it, for the purpose of signaling.

Signal Transduction

External signal is transmitted to the inside of a cell. Three steps: 1. Signaling molecule binding to specific receptor. 2. Activation of signal transduction pathway. 3. Production of cellular response

Ligand-gated ion channels

Present in the plasma membrane. Open or close ion channel once a ligand is bound.

Catalytic (enzyme-linked) receptors

Have enzymatic active site on cytoplasmic side of membrane. The enzyme is activated by ligand binding. Insulin receptor is an example

G-protein-linked receptor

Doesn’t act as an enzyme, but will bind different version of G-protein on inside of cell, when ligand bound on the outside. Activates secondary messengers

Secondary Messengers

Typically small molecules that move quickly throughout the cell. Can be made + destroyed quickly, help signal amplify throughout cell.

Homeostasis

Set of conditions under which living things can successfully survive

Negative Feedback Pathway (Feedback Inhibition)

Turning itself off using the end product of the pathway. End product inhibits the process from beginning.

Positive Feedback Pathway

Using end product to stimulate the pathway

Cell Division

When a cell turns from one cell to two cells

G₀

Some cells don’t divide or temporarily decide to not divide and enter this state

Cell Cycle

What a cell’s life cycle is known as

Interphase

One of two phases of the cell cycle, this one where cells spend most of the time. Cells grow and this phase can be divided into 3 parts: G₁, S, G₂.

G₁ phase

First of the G stages in interphase, where the cell produces all enzymes needed for DNA replication.

G₂ phase

Second of the checkpoint stages in interphase

S phase

When the cell replicates genetic material

Sister Chromatids

Where two chromatids are held together by a centromere. The two chromatids are identical to one another.

Centromere

The structure that holds the sister chromatids together. In order to be a chromosome, each chromatid needs its own of this structure

Cyclins

A special protein that regulates interphase

Cyclin-Dependent Kinases (CDKs)

A special protein that depends on another protein that helps regulate interphase

Cell Cycle Checkpoints

Control mechanisms that make sure that cell division is happening properly. Happens in eukaryotic cells

Apoptosis

Programmed cell death

Cancer

Happens when normal cells start behaving + growing abnormally and then spread to other parts of the body

Oncogenes

Mutated genes that make cancer

Tumor Suppressor Genes

Produce proteins that prevent the conversion of normal cells into cancer cells

Mitosis

Period when cell divides into two genetically identical daughter cells, important for growth, tissue repair + asexual reproduction. Made up of prophase, metaphase, anaphase and telophase

Prophase

This is when the cell is preparing to divide, the chromatin condenses into chromosomes.

Chromatin

The shape that DNA spends most of its time in, before condensing into chromosomes

Spindle Fibers

What centrioles dispense during prophase

Kinetochore

Structure that spindle fibers attach to on the centromere

Metaphase

When spindle fibers are attached to the kinetochore of each chromatid and the chromosomes are lined up in the middle of the cell

Metaphase Plate

Where all of the chromosomes line up

Anaphase

When the chromatids are pulled apart at the centromere and go to opposite ends of the cell

Telophase

When the nuclear membrane appears around each set of chromosomes and the nucleoli